Subsequent Events (Details)		1 Months Ended					2 Months Ended		12 Months Ended
	Feb. 23, 2017 $ / shares	Jul. 31, 2016	Jun. 30, 2016	May 31, 2016	Aug. 31, 2014 USD ($) $ / shares	Oct. 31, 2013	Feb. 22, 2017 USD ($) property $ / shares	Jan. 31, 2014	Dec. 31, 2016 USD ($) property $ / shares	Dec. 31, 2015 USD ($) $ / shares	Dec. 31, 2014 USD ($) $ / shares	Nov. 30, 2016 USD ($)	Feb. 29, 2016 $ / shares
Subsequent Event
Revolving credit facility outstanding balance									$ 0	$ 0
Proceeds from revolving credit facilities									$ 951,000,000	827,000,000	$ 1,828,000,000
Number of properties sold | property									712
Proceeds from disposition of properties, net									$ 88,590,000	0	0
Proceeds from issuance of Class A common shares									$ 102,830,000	$ 0	$ 308,435,000
Dividends declared on common shares (in dollars per share) | $ / shares									$ 0.2	$ 0.2	$ 0.2
Class A common shares
Subsequent Event
Common shares									$ 2,427,000	$ 2,072,000
Proceeds from issuance of Class A common shares					$ 313,300,000
Common shares, par value (in dollars per share) | $ / shares					$ 0.01				$ 0.01	$ 0.01			$ 0.01
Offering costs					$ 4,900,000				$ 227,000	$ 0	$ 0
Class B common shares
Subsequent Event
Common shares									$ 6,000	$ 6,000
Common shares, par value (in dollars per share) | $ / shares									$ 0.01	$ 0.01
Series A Participating Preferred Stock
Subsequent Event
Preferred Shares dividend rate						5.00%			5.00%	5.00%	5.00%
Series B Participating Preferred Stock
Subsequent Event
Preferred Shares dividend rate								5.00%	5.00%	5.00%	5.00%
Series D Perpetual Preferred Stock
Subsequent Event
Preferred Shares dividend rate				6.50%					6.50%
Series E Perpetual Preferred Stock
Subsequent Event
Preferred Shares dividend rate		6.35%	6.35%						6.35%
Subsequent Events
Subsequent Event
Number of properties sold | property							60
Proceeds from disposition of properties, net							$ 6,300,000
Number of properties acquired | property							200
Aggregate purchase price of properties acquired							$ 32,700,000
Subsequent Events | Class A common shares
Subsequent Event
Common shares							$ 200,000
Common shares, par value (in dollars per share) | $ / shares							$ 21.27
Proceeds from sale of stock, net of issuance costs							$ 5,200,000
Offering costs							100,000
Shares reserved for future issuance							290,700,000
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.05
Subsequent Events | Class B common shares
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	0.05
Subsequent Events | Series A Participating Preferred Stock
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.3125
Preferred Shares dividend rate	5.00%
Subsequent Events | Series B Participating Preferred Stock
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.3125
Preferred Shares dividend rate	5.00%
Subsequent Events | 5.50% Series C participating preferred shares
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.34375
Preferred Shares dividend rate	5.50%
Subsequent Events | Series D Perpetual Preferred Stock
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.40625
Preferred Shares dividend rate	6.50%
Subsequent Events | Series E Perpetual Preferred Stock
Subsequent Event
Dividends declared on common shares (in dollars per share) | $ / shares	$ 0.39688
Preferred Shares dividend rate	6.35%
Line of Credit | Credit facility
Subsequent Event
Revolving credit facility outstanding balance									$ 0	$ 0
Line of Credit | Credit facility | Subsequent Events
Subsequent Event
Revolving credit facility outstanding balance							0
Term Loan Facility
Subsequent Event
Term loan facility									321,735,000	0
Term Loan Facility | Secured Debt
Subsequent Event
Term loan facility									325,000,000	$ 0
Term Loan Facility | Secured Debt | Subsequent Events
Subsequent Event
Additional proceeds drawn from term loan							25,000,000
Term loan facility							350,000,000
At the Market - Common Share Offering Program | Class A common shares
Subsequent Event
Proceeds from issuance of Class A common shares									104,000,000
Proceeds from sale of stock, net of issuance costs									102,800,000
Offering costs									1,200,000
Shares reserved for future issuance												$ 400,000,000.0
Remaining available for future shares									$ 296,000,000
At the Market - Common Share Offering Program | Subsequent Events | Class A common shares
Subsequent Event
Proceeds from issuance of Class A common shares							$ 5,300,000